These machines certainly aren't secret, but they might as well be, because so many gym members never use them.

They don't know what they're missing. If you belong to a gym and use the same old free weights and machines all the time, you're not getting the biggest bang for your workout buck. Your body has adapted, and is no longer gaining.

That may be why you're not getting your illusive dream body: the six-pack abs and tight, toned core, or the muscles and coordination that make you a better athlete. Solution: Try some obscure equipment and exercises.

They may not be part of your regular workout routine, but if you add these exercises to your program, guaranteed it will wake up slacking muscles — and as an extra benefit, help work off stubborn fat.

One of the most valuable, and most ignored devices in the gym is the oblique bench. This unassuming piece of equipment is perhaps the most versatile machine in the gym for a core workout. It doesn't have a limited range of motion as cable machines do, and it allows you to use various angles to work every part of your core. That includes the obliques — the muscles on the side of your torso, as well as the spinal erectors, muscles on each side of your spine.

Adjust the bench so the top reaches no higher than your hips. You need to be able to freely bend over the top and come back up to get the required resistance. Use it with body weight alone, or while holding a weight plate to the upper chest. Different positions, even slight changes in angles, will work the entire girdle of muscles that surround the waist and hips.

First, some muscle info: Your body position when you do an exercise determines how your muscles will respond. Only the muscle fibers that are directly recruited by the resistance will pump up — meaning, fill with blood, when worked. That's why you should turn to slightly different positions during a set. If you just work the belly of each muscle, it will leave the ends of the muscle undeveloped, creating an imbalanced look. That's why position counts on the oblique bench. When bending sideways to work your obliques, you'll feel different core areas being worked if you bend over with your butt on the padded bench, or bend over with your hip on the bench. Use both positions; hip placement will get your abs more involved. Put your shoulders in different positions; twist your body so shoulders are facing the floor or a little more upward or downward.

The most important thing to remember: Never curve your spine while using this bench. Your back should always be straight between the shoulders and butt, and you should never bend at the waist. Only bend at the hips, where your legs meet your core. If you curve your back, you're putting the entire weight of your upper body and any weight you're holding, all on a few spinal vertebrae. It's a surefire way to injure your back.

Don't ever bend your spinal column on the oblique bench.Concentrate on feeling which muscles — and which parts of the muscles — are being worked. Change the position of your lower body on the bench to include a few sets that incorporate your abs; you'll know if they're getting exercised by the way they feel.

Use this machine as a regular part of your fitness routine. It will make you better on the field, on the course or in a bathing suit.

Wina Sturgeon is the editor of the online magazine Adventure Sports Weekly, which offers the latest training, diet and athletic information.